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Finding the Fourth Proportional to 137.21, 189.34 and 78.20

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Solution

The fourth proportional to 137.21, 189.34 and 78.20 is: 107.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    137.21 : 189.34 = 78.20 : x
  2. Step 2: Convert to fraction form
    137.21/189.34 = 78.20/x
  3. Step 3: Cross multiply
    137.21x = 189.34 × 78.20
  4. Step 4: Simplify right side
    137.21x = 14,805.25
  5. Step 5: Solve for x
    x = 14,805.25/137.21
  6. Step 6: Final answer
    x = 107.91

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.